Molecular Cloning And Sequence Analysis Of Flower-bud Induction Related Genes In Apple

Apple (Malus domestica Borkh.), one of the most important fruit tree resources in the world, has high nutritional value and economic value. Its flower bud is mixed bud and forms in the year before flowering and fruiting, but it is difficult to control the formation of flower bud, and the phenomenon of biennial bearing that influencing the production is prone to appears by poor management. In order to provide theoretical basis and guidance for the regulation of the flower bud differentiation of apple and other wood fruit trees, the flower bud initiation related genes were subsection cloned from the apple race of Gala in this study, and the protein amino acid sequences encoded by the genes were homology and bioinformatics analyzed. The main results are as follows:1 The optimum annealing temperatures for every segments of flower bud initiation related genes were defined: the optimum annealing temperature for MdAFL2-1 was 64℃; the optimum annealing temperature for MdAFL2-2 was 63℃; the optimum annealing temperature for MdMADS5-1 was 57℃; the optimum annealing temperature for MdMADS5-2 was 55.5℃.2. The MdAFL2 of 1293bp was gained by sequence assembly, and its ORF was 1233bp, encoding 410 amino acid residues. The molecular mass of the predicted protein was 45.37 KDa; the theoretical isoelectric point was 6.44; the instability index was 41.14 and the hydrophilicity was weak. The predicted protein contained FLO_LFY domain; it was predicted that the irregular coil regions, the main conformation, accounted for 46.83% in all the structure. The homology analysis showed that the similarity of MdAFL2 and LFY homologous proteins from other species was more than 75%, and the similarity of MdAFL2 and LFY homologous proteins from other apple subfamily was more than 98%.3. The MdTFL1 of 675bp, containing the ORF of 519bp, encoded 172 amino acid residues. The molecular mass of the predicted protein was 19.31 KDa; the theoretical isoelectric point was 8.82; the instability index was 43.87 and the hydrophilicity was weak. The predicted protein contained PEBP_euk domain; it was predicted that the irregular coil regions, the main conformation, accounted for 58.14% in all the structure. The homology analysis showed that the similarity of MdTFL1 and TFL1 homologous proteins from other species was more than 82%, and the similarity of MdTFL1 and TFL1 homologous proteins from other apple subfamily was more than 95%. 4. The MdMADS5 of 894bp was gained by sequence assembly, and its ORF was 720bp, encoding 410 amino acid residues. The molecular mass of the predicted protein was 27.98 KDa; the theoretical isoelectric point was 8.70; the instability index was 53.72 and the hydrophilicity was weak. The predicted protein contained K-box domain, MADS_MEF2_like domain which was specific to MADS-box gene family; it was predicted that the irregular coil regions, the main conformation, accounted for 46.83% in all the structure. The homology analysis showed that the similarity of MdMADS5, MADS and AP1 homologous proteins from other species was more than 80%, and the similarity of MdMADS5 and MADS, AP1 homologous proteins from other apple subfamily was more than 96%.